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Volcanoes

There are several ways in which a volcano can form, just as there are several different kinds of volcanoes. Volcanismis part of the process by which a planet cools off.

Hot magma, rising from lower reaches of the Earth, eventually, but not always, erupts onto the surface in the form of lava. During the eruption of a volcano, flowing lava and ashform a large cone. This cone is what we know as a volcano.

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Volcanoes form when hot material from below risesand leaks into the crust. This hot material, called magma, comes either from a melt of subducted crustal material, and which is light and buoyant after...more

Ash is made of millions of tiny fragments of rock and glass formed during a volcanic eruption. Volcanic ash particles are less than 2 mm in size and can be much smaller. Volcanic ash forms in several ways...more

Cinder cones are simple volcanoes which have a bowl-shaped crater at the summit and only grow to about a thousand feet, the size of a hill. They usually are created of eruptions from a single opening,...more

When two sections of the Earth's crust collide, one slab of crust can be forced back down into the deeper regions of the Earth, as shown in this diagram. This process is called subduction. The slab that...more

Mount St. Helens, a volcano in Washington on the west coast of the United States, has been quiet for 18 years but now it is quiet no more! It has been puffing steam and ash as scientists look for clues...more

Scientists are using information they have from past volcanic eruptions to better understand strong volcanic plumes. They have observed that in some volcanic eruptions, there is a spontaneous formation...more

Lava can move in broad flat lava flows, or it can move through tight channels or tubes. Lava flows tend to cool quickly and flow slowly. The fastest lava outside of channels moves at about 6 mi/hr an easy...more